1. Field of the Invention
The invention relates to the field of power supplies and voltage regulators for microprocessors and the like.
2. Prior Art and Related Art
Voltage regulators sometimes use external resistors to assure a predetermined load line and offset voltage. For instance, the set-points assure that at low activity during an active mode, Vcc approximates the maximum power supply voltage for the microprocessor, and at maximum current load the regulator provides the minimum acceptable Vcc to the microprocessor. The resistors also provide the offset potential that allow the correct voltage for sleep modes to compensate for leakage over the operating temperature range of the microprocessor.
These resistors are often selected based on the worse case part. As a practical matter, a voltage regulator for a given platform may be tuned to the highest frequency part that will be used in that platform. This reduces the efficiency since the load line and offset voltage are usually non-optimal for a given processor.
Whenever the load line is not optimal, more power than necessary is consumed. This is particularly important for microprocessor in mobile personal computers since it shortens battery life.
See U.S. Pat. No. 5,926,394 and co-pending application Ser. No. 09/148,033; filed Sep. 3, 1998; entitled, xe2x80x9cMethod and Apparatus for Reducing the Power Consumption of a Voltage Regulatorxe2x80x9d assigned to the assignee of the present invention.